PROJECT SUMMARY: Nonhealing skin wounds are a major source of morbidity worldwide and becoming more of a burden due to an increase in health care costs, an aging population, and growing incidence of diabetes. Non-healing skin wounds occur in nearly 25% of diabetic patients, and ~6% are admitted to the hospital for wound-related treatment, which if not successful, can lead to limb amputation or death. While more advanced treatments are needed, cutting edge, multi-component technologies such as hydrogels or scaffolds loaded either with cells and/or drugs have not achieved clinical impact. Failure of new candidate treatments is often due to poor tissue integration, insufficient drug release profiles, and loss of biological (cell or growth factor) activity upon delivery into a hostile wound microenvironment characterized by high concentrations of cytokines, proteases, and cytotoxic reactive oxygen species (ROS). The overall goal of the current project is to develop and apply a next generation, shear-thinning, and ROS scavenging hydrogel that comprises a hybrid of ROS responsive nanoparticles (NPs) and hyaluronic acid (HA), a natural extracellular matrix component. The shear thinning hydrogel mechanical properties will be achieved through guest-host chemistry based on adamantane (AD) and beta-cyclodextrin (CD), which form reversible, mechanically-stabilizing inclusion complexes. NPs will be surface functionalized with AD, and HA polymers will be modified with CD; when these two components are mixed, they form shear-thinning solutions that rapidly self- heal to form stable hydrogels within the tissue defect. The HA component is included because of its precedent for efficacious use in wound healing devices/dressings, while the NP is designed to have ROS reactivity (making it inherently antioxidant). The NPs can also be ?pre-loaded? with drugs prior to hydrogel formation, providing a mechanism for sustained drug release to the wound site. The first aim of this project will be to optimize the proposed NP/HA hydrogel system by tuning polymer molecular weight and AD/CD modification density on the NP and HA components, respectively. The second aim will involve testing of lead candidate hydrogels in vivo to assess tissue response, sustained model drug release, and ROS scavenging / protection of therapeutic stem cells loaded into the device. In the third aim, we will compare the leading NP/HA hydrogel formulation to a HA-based, clinical control material for healing benefit alone on in combination with either stem cells or a small molecule drug that activates the pro-healing transcription factor HIF1alpha. These studies, designed to establish proof of concept for clinical efficacy, will be completed in extremely challenged (ischemic and genetically-driven enhanced ROS phenotype) diabetic wound models. Our multidisciplinary team, including a bioengineer, chemist, wound healing expert, and stem cell expert, is poised to achieve the proposed goals toward establishing a new wound healing platform.